(a) Field of the Invention
The present invention relates to a method for manufacturing a magnetic tunnel junction device. More particularly, it relates to a method for manufacturing a magnetic tunnel junction device using an amorphous material with perpendicular magnetic anisotropy.
(b) Description of the Related Art
Recently, various types of memories have been developed. For example, a magnetic random access memory (MRAM), a phase-change random access memory (PRAM), and a resistive random access memory (RRAM) have been developed.
The MRAM uses a magnetic tunnel junction (MJT) element as a data storage element. The magnetic tunnel junction element included in a memory cell is based on ferromagnetic tunnel junction properties. The magnetic tunnel junction element consists of two magnetic layers separated by an insulating layer, and the current flows in the insulating layer through the tunneling mechanism. Here, when the relative magnetization directions of the two magnetic layers are parallel to each other, the magnetic tunnel junction element has low resistance. In contrast, when the two magnetic layers have an antiparallel magnetization configuration, the magnetic tunnel junction element has high resistance. The low resistance and the high resistance indicate digital data, respectively, corresponding to 0 and 1.
Thermal stability is defined as the ability of retaining the digital data for a long period of time. The thermal stability is proportional to anisotropy energy of the magnetic layer of the magnetic tunnel junction element. In the majority of cases, the ferromagnetic materials used in the magnetic tunnel junction element have an in-plane magnetic anisotropy, for example, represented by shape anisotropy energy, and therefore the total anisotropy energy is small. In order to solve this problem, a ferromagnetic material with perpendicular magnetic anisotropy, for example, represented by high crystalline anisotropy energy, is used as a material of the magnetic tunnel junction element. Accordingly, the total anisotropy energy of the magnetic tunnel junction device is large so that the magnetic tunnel junction device can have superior thermal stability with a small volume.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.